Coupling and rod system for rock drills



Jan. 28, 1969 J. D. DITSON ETAL 3,424,479

COUPLING AND ROD SYSTEM FOR ROCK DRILLS Filed Jan. 11, 1966 Sheet 1 Of 2 FIG. 2

INVENTORS J. D. 0/ 7' SON JA MES E CANTREL Sheet Filed Jan. 11, 1966 FIG. 5]

VENTOR.$ FIG. FIG. 7 J.0.'D/T$0N JAMES E CANTREL United States Patent 3,424,479 COUPLING AND ROD SYSTEM FOR ROCK DRILLS J. D. Ditson, West Portal, N.J., and James F. Cantrel, Easton, Pa., assignors to Ingersoll-Rand Company, New York, N.Y., a corporation of New Jersey Continuation-impart of application Ser. No. 455,098, May 12, 1965. This application Jan. 11, 1966, Ser. No. 525,009 US. Cl. 285-84 6 Claims Int. Cl. F16] 21/00, 15/00, 55/00 ABSTRACT OF THE DISCLOSURE A rock drill coupling and rod system comprising a coupling member having a bore provided with a pair of circumferentially offset, overlapping threads adapted for connecting a plurality of rods in aligned relationship. In addition, a drill rod provided with a circumferential attachment thread which extends continuously throughout the length of the drill rod.

This application is a continuation-in-part of United State Patent application Ser. No. 455,098, which was filed May 12, 1965, and now abandoned.

This invention relates to rock drill apparatus and has particular reference to a coupling and rod system for rock drills. More specifically, the present invention comprises the provision of a new and improved rock drill coupling and rod system wherein the coupling member is self-locating upon the drill rods and the drill rods are constructed and arranged to enhance the strength and durability of the coupling member.

Basically, a coupling and rod system or coupled rod system for a rock drill comprises a plurality of drill rods which are connected in longitudinal alignment by a coupling member. conventionally, this coupling member is characterized as being of the full bridge type, the semibridge type, or the bridgeless type.

A full bridge type coupling member includes a bridge or abutment which is located midway in the coupling member and extends transversely thereacross. The drill rods coupled thereby are screwed into the coupling member until each abuts the bridge or abutment such that rotary and longitudinal energy of the driving drill rod is transmitted through the coupling member to the driven drill rod. This form of coupling is undesirable in that the coupling member is subject to frequent premature failure due to this necessity that all of the energy transmitted between the drill rods pass through the relatively small mass of the coupling member.

A semibridge type coupling member also includes a bridge or abutment which is located midway in the coupling member and extends transversely thereacross. In this type of coupling member, however, a bore is formed through the bridge or abutment; and a reduced diameter button of smaller cross section than this bore is formed upon the adjacent ends of each of the coupled drill rods such that, upon insertion of the rods into the coupling member, the buttons are in engaging relation. This form of coupling thus overcomes the beforedescribed weakness of the full bridge type coupling member by permitting energy to be transmitted directly from one drill rod to ICC the other without energy transfer to the coupling member. However, it has been found that the formation of the buttons necessary for this type of coupling reduces the engagement length of the attachment thread in the coupling member for any given length thereof and necessitates additional expense and labor during the reconditioning of the drill rods such as limits the reconditioning flexibility of the coupled rod system.

As conventionally constructed, a bridgeless type coupling member is heavily dependent upon the length of the threaded portions of the drill rods to properly locate the rods. Furthermore, this type of coupling usually requires the formation of a shoulder upon each of the rods to assist in limiting the entrance thereof into the coupling member. It has been found that this shoulder frequently causes premature failure of both drill rods and coupling members.

An object of the present invention is to provide a new and improved rock drill coupling and rod system wherein the coupling member is self-locating upon the drill rods and the drill rods are particularly constructed and arrange-d to enhance the strength and durability of the coupling member.

Another object of the invention is to provide a new and improved rock drill coupling and rod system of the type set forth wherein the coupling member is self-locating upon the drill rods without the necessity for bridges, abutments, buttons, shoulders, or other protruding or projecting elements which might cause premature coupling or rod failure.

Another object is to provide a new and improved rock drill coupling and rod system of the type set forth wherein the drill rods are particularly constructed and arranged to facilitate reconditioning of the coupling and rod system and to increase the operative life of all components thereof.

Another object is to provide a new and improved coupling and rod system of the type set forth wherein the drill rods are particularly constructed and arranged to clean the hole being drilled.

Another object is to provide a new and improved drill rod which is particularly constructed and arranged to increase the strength of the rod as well as to facilitate its reconditioning.

Another object is to provide a new and improved coupling which is particularly constructed and arranged to be self-locating upon the drill rods which it connects.

Other objects and advantages of the invention will be apparent from the following description taken in connection with the accompanying drawings. It will be understood that changes may be made in the details of construction and arrangement of parts shown and described as the preferred form of the invention has been given by way of illustration only.

Referring to the drawings:

FIG. 1 is an elevational view illustrating the coupling and rod system provided by the present invention in operative position within a hole being drilled;

FIG. 2 is a partially broken away, enlarged perspective view of the coupling and rod system of the invention;

FIG. 3 is a fragmentary sectional view of the coupling and rod system;

FIG. 4 is an enlarged sectional view of the coupling member of the coupling and rod system;

FIG. 5 is a fragmentary view of one of the drill rods of the coupling and rod system;

FIG. 6 is a sectional view through the drill rod shown in FIG. 5 taken on line 6-6 of FIG. 5 looking in the direction of the arrows; and

FIG. 7 is another sectional view through the drill rod shown in FIG. 5 taken on line 77 of FIG. 5 looking in the direction of the arrows.

Referring more particularly to the drawings wherein similar reference characters designate corresponding parts throughout the several views, FIG. 1 illustrates generally a coupling and rod system constructed in accordance with the present invention which is operatively disposed within a hole 10 being drilled. More particularly, as will be seen from FIG. 1, the coupling and rod system comprises a first drill rod 12, a second drill rod 14, and a coupling member 16 which fixedly connects the drill rods 12 and 14 in conjoined longitudinal alignment.

The first drill rod 12 includes an end portion 112a which projects longitudinally from the hole 10 and is operatively connected to a rock drill (not shown) such that the first drill rod 12 receives longitudinal and rotary movement from the rock drill during the operation thereof. The coupling member 16 transmits the rotary movement from the first drill rod 12 to the second drill rod 1 4 and maintains the first and second drill rods 12 and 14, respectively, in longitudinal alignment for transmission of longitudinal energy directly from the first drill rod 12 to the second drill rod 14. The second drill rod 14 is threaded into a drill bit 18 which is located at the drilling surface 20 and directly transmits this rotary and longitudinal movement to the drill bit 18. Thus, it will be seen that the first drill rod 12, the second drill rod 14, and the coupling member 16 which comprise the coupling and rod system of the present invention cooperate to support the drill bit 1 8 at the drilling surface 20 and transmit drilling movements thereto.

The first drill rod '12 and the second drill rod 14 include cooperating axial bores 22 adapted to supply air or other suitable fluid to the drilling surface 20 for the removal of cuttings therefrom and are identical in construction such as to be readily and simply interchangeable. Due to this identity in construction of the drill rods 12 and 14, and for the purposes of brevity and clarity of description, the details of construction of the first drill rod 12, only, will be herein specifically described. It will be understood, however, as shown by the application of reference characters upon the drawings, that all of the detailed description given herein with regard to the construction of the first drill rod 12 is equally applicable to the construction of the second drill rod 14.

As shown in FIGS. 2 and 5 through 7, the first drill rod 12 includes a cylindrical body 13 which is constructed of uniform circular cross section and includes a constant diameter throughout its length. This uniformity in the cross-sectional diameter of the body 13 of the first drill rod 12 avoids the stress raising factors and possible causes of premature rod failure that are inherently associated with variations in rod cross section and ensures a long operative life of the first drill rod 12. The construction of the body 13 of the first drill rod 12 of circular cross section facilitates the provision of a lightweight drill rod for any required length thereof and facilitates the selflocating of the coupling member 16 upon the drill rods 12 and 14.

A single thread 24 is formed circumferentially around the body 13 of the first drill rod 12 and extends continuously throughout the length thereof. The thread 24 is a symmetrical thread of spiral form and is of the single pitch type wherein the pitch of the thread equals the lead thereof. Thus, one revolution of the first drill rod 12 through a 360 angle will axially advance the first drill rod 12 into a similarly threaded bore the longitudinal distance between a point on one spiral of the thread 4 24 and a corresponding point on the succeeding spiral of the thread 24.

The thread 24, as illustrated in FIG. 5, is formed with a helix angle a of not more than 15. This formation of the helix angle on has been found to be important for the proper locking of the coupling member 16 and the drill bit 18 to the drill rods 12 and 14. The formation of the helix angle a greater than 15 has been found to provide a thread form which is too steeply inclined to provide a proper locking relationship between the drill rods 12, 14 and the coupling member 16 and drill bit 18.

The thread 24-, furthermore, is formed by the rolling process such that the lines of the thread as well as the length thereof are continuous throughout the length of the drill rod 12 and the drill rod 12 is free from abrupt variations in cross section. The thread 24 serves as an attachment means for securing the first drill rod 12 to the coupling member 16 and, as will be seen from FIGS. 2 and 5, is provided, on its crest, with a circumferential groove 26 which extends continuously throughout its length. The groove 26 is adapted to carry a lubricant which may be wiped or otherwise suitably disposed upon the thread 24 for lubricating the portion thereof passing internally into the coupling member 16.

As the first drill rod 12 and the second drill rod 14 are thus continuously threaded throughout their lengths, the form and quality of the thread 24 provided by the rod manufacturer endures throughout the operative lives of the drill rods 12 and 14. Therefore, the process of reconditioning a failed or broken rod is simplified to the extent that it merely comprises the cutting off of the failed or broken portion of the rod; and the rod manufacturer may employ special materials and unusual heat treatment processes in the fabrication of the rod without consideration of the field reconditioning problems that previously hereto have limited the processes and materials employed in manufacturing the rod.

Furthermore, the continuous lines of the thread 24 upon each of the drill rods 12 and '14 function as an Archimedes screw to remove the mud collar that conventionally for-ms above the drill bit 18 and direct such from the hole 10 during the operation of the rock drill (not shown). More specifically, as will be seen from the direction of the arrows in FIG. 1, the mud collar is directed by the thread 24 on the second drill rod 14 and the pressure circumferentially around the coupling member '16 to the thread 24 on the first drill rod 12 which, in turn, directs this mud collar from the hole 10 to a point (not shown) where the mud may be collected for disposal purposes.

The coupling member 16, as will be seen from FIGS. 2 through 4, is basically of cylindrical configuration and includes an axial bore 27 of constant diameter which is adapted to receive the first and second drill rods 12 and 14, respectively. A symmetrical thread 28 of spiral form and single pitch type is started within the bore 27 from each of the opposing longitudinal ends of the coupling member 16. The threads 28 are adapted to mesh with the threads 24 upon the drill rods 12 and 14 to retain the drill rods 12 and 14 within the coupling member 16 and, as will be later herein shown, are constructed and arranged to facilitate the self-locating of the coupling member 16 upon the drill rods 12 and 14. The direction of threading of the drill rods 12 and 14 in the bore 27 is, of course, in the direction of the rotation transmitted by the rock drill (not shown) such that there is an inherent tendency to thread the drill rods 12 and 14 into gheucoupling member 16 during the operation of the rock The initiating of the threads 28 is carefully mismatched by one-half of the lead thereof such that the helix root 30 of each of the threads 28 is a continuation of the crest 32 of the other thereof at the junctures of the threads 28. The depth of each of the threads 28 extends beyond the longitudinal midpoint of the coupling member 16 such that each of the threads 28 is terminated in overlapping relationship with the other thereof. That is to say, each of the threads 28 is terminated immediately beyond the termination of the thread 28 initiated from the opposite end of the coupling member 16 such that, as shown in FIG. 4, the crest 32 of each of the threads 28 merges into the helix root 30 of the other thereof.

During the formation of the threads 28, the cutting tool (not shown) used to form such within the bore 27 is rapidly withdrawn immediately after the cutting of the final spiral of each of the threads 28. Thus, the final spiral of each of the threads 28 is terminated without the formation of an undercut such as might weaken the coupling member 16; and an abrupt limiting stop is formed at the terminating end of each of the threads 28.

Due to the beforedescribed construction of the coupling member 16; and an abrupt limiting stop is formed at the 14, respectively, is able to pass the terminal point of the thread 28 initiated from the longitudinal end of the coupling member 16 opposite to that from which the rods 12 and 14 are inserted. Neither of the drill rods 12 and 14 is able, however, to pass completely through the coupling member 16 due to the separate entities of each of the threads 28. Thus, it will be seen that the drill rods 12 and 14 will abut within the coupling member 16 before being prevented by the threads 28 from further movement therein.

Thus, the coupling member 16 which is provided by the present invention is self-locating upon the drill rods 12 and 14 due to the beforedescribed construction of the threads 28 and their interaction with the threads 24 on the drill rods 12 and 14. Furthermore, as this selfalocating of the coupling member 16 is dependent only upon the construction of the meshing threads 24 and 28, it will be seen that there is no necessity for bridges, abutments, buttons, shoulders, or other protruding or projecting elements which might cause premature rod or coupling failure.

As the drill rods 12 and 14 are of constant cross section and are continuously threaded throughout their lengths, it will be seen that they include no variation in cross section which might result in early rod failure and have no shoulders or abutments which might engage the coupling member 16 such as to cause premature failure thereof. Also, this continuous threading of each of the drill rods 12 and 14, as has been previously herein shown, facilitates reconditioning of the coupling and rod system and assists in the removal of mud from the hole 10.

The operation of the coupling and rod system of the present invention is believed to be apparent from the foregoing.

From the foregoing it will be seen that we have provided new and improved means for accomplishing all of the objects and advantages of our invention.

What is claimed is:

'1. A rock drill coupling and rod system comprising:

a first rod having a circumferential thread on at least one end;

a second rod having a circumferential thread on at least one end;

a coupling member connecting said first and second rods in conjoined longitudinal alignment having an axial bore therethrough receiving said threaded ends of said first and second rods;

a first thread within said bore initiated adjacent one end of said coupling member and terminating intermediate the ends of said coupling member;

a second thread within said bore initiated adjacent the other end of said coupling member and terminating intermediate the ends of said coupling member;

said threads all being of the same hand, said first and second threads being of the same lead, and the threads on each of said rods extending a distance sufficient to allow said rod ends within said coupling member to abut one another; and

said first and second threads being initiated circumferentially offset by a space of substantially one-half of their lead and extending in overlapping relationship such that the helix root of each of said first and second threads terminates at the crest of the other thereof.

2. A rock drill coupling comprising:

a body having a bore, adapted to receive the adjacent threaded ends of a pair of aligned rods, which is of constant diameter and extends longitudinally through said body;

a first thread within said bore initiated adjacent one end of said body and terminating intermediate the ends of said body;

a second thread within said bore initiated adjacent the other end of said body and terminating intermediate the ends thereof, said first and second threads being of the same lead and hand; and

said first and second threads being initiated circumferentially offset by a space of substantially one-half of their lead and extending in overlapping relationship such that the helix root of each of said threads terminates at the crest of the other thereof.

3. A rock drill coupling comprising:

a body having a bore, adapted to receive the adjacent threaded ends of a pair of aligned rods, which is of constant diameter and extends longitudinally through said body;

a first thread within said bore initiated adjacent one end of said body and terminating intermediate the ends of said body;

a second thread within said bore initiated adjacent the other end of said body and terminating intermediate the ends thereof, said first and second threads being of the same lead and hand; and

the helix roots of said first and second threads being offset by substantially one-half of their lead and terminating in overlapping relationship.

4. A drill rod comprising an elongated body including a bore axially therethrough and having a single, spiral, single pitch, attachment thread which is roll formed on said body to extend circumferentially therearound continuously throughout the length of said body, the helix angle of said attachment thread being less than 15 degrees, and a single continuous groove on the crest of said attachment thread continuously throughout its length.

5. A drill rod comprising an elongated body including a bore extending axially therethrough and having a rollformed helical attachment thread extending circumferentially therearound continuously throughout the length of said body, the helix angle of said attachment thread being less than 15 degrees, and a continuous helical groove extending along the entire length of the crest of said attachment thread.

6. A rock drill coupling and rod system comprising:

a first rod having a roll formed, attachment thread which exteinds circumferentially around said first rod throughout the length of the latter;

a second rod having a roll formed, attachment thread which extends circumferentially around said second rod throughout the length of the latter; and

a coupling connecting said first and second rods in longitudinal alignment, said coupling including a body having a constant diameter bore receiving adjacent ends of said first and second rods;

said bore being provided with a first thread initiated adjacent one end of said body and terminating interinediate the ends of said body, and a second thread initiated adjacent the other end of said body and terminating intermediate the ends thereof;

said first and second threads being of the same lead and hand, and the helix roots of said first and second threads being offset by substantially one-half their lead and terminating in overlapping relationship.

(References on following page) 7 8 References Cited FOREIGN PATENTS P \ITS 627,065 9/1961 Canada. UNITED STATES ATEL 338,352 5/1920 Germany.

1,904,675 4/1933 Boyer 285-390' 26,810 11/1909 Great Britain. 2,669,469 '2/1954 Finch 285-390 5 513,952 2/1955 Italy. 1,344,032 6/1920 Greenfield 285417X 1,642,183 9/1927 Thurston 285-117 X CARL W. TOMLIN, 'y Exammeh 1,807,494 5/ 1931 Proctor 85-4 DAVE W. AROLA, Assistant Examiner. 1,952,996 3/1934 Landgraf 285-117 2,827,313 3/1958 Conner 85 46x 10 3,211,484 10/1965 Karlsson et a1. 285-390, 417; 287117; 8546; 175-394; 641

UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION Patent No. 3 ,424 ,479 January 28 1969 J. D. Ditson et a1.

It is certified that error appears in the above identified patent and that said Letters Patent are hereby corrected as shown below:

"member 16; and an abrupt limiting stop each of the first line 56, "exteinds" Column 5, line 17, is formed at the" should read member 16,

and second drill rods 12 and Column 6 should read extends Signed and sealed this 9th day of December 1969.

ISEAL) Attest:

Edward M. Fletcher, Jr.

Attesting Officer Commissioner of Patents WILLIAM E. SCHUYLER, JR. 

